xerxes
Been here a while!
Posts: 1,115
|
Post by xerxes on Sept 12, 2006 15:25:44 GMT
I had a Monica 2, NOS DAC board and a Pimeta headhone amp board and thought I'd do something useful with them and came up with this: You can see some more pictures, including some of nekked PCBs, for Mike, HERE.
|
|
rickcr42
Fully Modded
Rest in peace my good friend.
Posts: 4,514
|
Post by rickcr42 on Sept 13, 2006 2:19:12 GMT
damn fine job,a very "balanced" look that no doubt has a user friendly feel on a desk top.My only concern is heavy enough ? My main beef with most things I make not having an internal power supply transformer (even though with very good reasons for having such outside the box) and with no other heavy metal is the tendency to "walk" on the shelf/surface in actual use and I find i am always straightening the units.This aggravates the sh*t out of me so I end up adding weights to everything light. And bfore you ask : Yes.I DO drive myself crazy
|
|
xerxes
Been here a while!
Posts: 1,115
|
Post by xerxes on Sept 13, 2006 5:40:36 GMT
The main reason the PSU is in a separate box is that there wasn't enough room in one. And larger cases weren't available unless I paid a lot more than the cost of a couple of hammond cases and I know how much you like them Rick. The PSU probably weighs a couple of kilos all up, so that won't walk off. The DAC/Amp is lighter, but not so light that it wanders around. While the hammond cases are aluminium, these larger cases are quite thick, probably about 2mm minimum and thicker in places with the ribbing/card slots, so they alone weigh a fair bit. Once you've added all the "furniture", knobs, sockets, etc., it soon adds up. I also used some fairly grippy rubber feet so they tend not to slide around easily on the desk or one another. If it was an issue, I could always add some "ballast" to the DAC/Amp, theres plenty of room inside. Alternatively I could use some nuts, bolts and spacers and fix the lid of the PSU to the base of the DAC/Amp, so that once the lid of the PSU is slid into position and the end plates attached the two units are fixed together. Or the simplest solution of all, put the PSU on the top.
|
|
|
Post by southpaw on Sept 13, 2006 12:22:11 GMT
Damm fine job Xerxes! Now if I could just get started on my first project the next one would be just around the corner
|
|
rickcr42
Fully Modded
Rest in peace my good friend.
Posts: 4,514
|
Post by rickcr42 on Sept 13, 2006 13:30:06 GMT
Yeah Babee ! Mongo like Hammonds.YUMMY ! Ext PSU or at the minimum external power transformer is never a bad idea because it simplifies the layout and like you said can make for a compact case.Another advantage to "all outside the box" power sources is the ability to Plug 'N Play various power supplies in an attempt to fine "THE ONE" if you are a pain in the ass like me always looking for that greener grass ;D Might be a Grado Headphone Cable specific deal at work here.This is a very heavy duty cord and has some serious weight so when hanging from the front of of a small rack/shelf mounted amp can be heavier than the total amp weight causing it to "scew" on the shelf unless you sit right by the amp.I have even been known to lose a couple of front panels to "whoopsy" when the little pricks hit the floor when my air guitars were in full swing ;D But that years ago.I have since moved on to "heavy metal under the hood" amps in both my solid state Class-A nightmares and my tube based bank breakers I agree.nothing worse than hard rubber feet meeting a smooth surface.Has a tendency to sliiiiiiiiiiiiiiide around a bit and again if a headphone amp can go to "whoopsie !" plan on sailing it do you ? ;D I wonder what the EU would think of the SOLID LEAD WEIGHTS I have at times used to anchor some of my more wimp-weight efforts ? The brass ingots would pass muster but I think SOLID LEAD would send one of those inspectors looking for PPM lead measures into cardiac arrest all in all a nice job.Don't pay attention to me man 'cause everyone knows my middle name is OVERKILL (among others )
|
|
xerxes
Been here a while!
Posts: 1,115
|
Post by xerxes on Sept 20, 2006 11:51:07 GMT
I've hit a snag! I've used the DAC-AMP several times, often for an hour or two at a time and haven't had any problems, everything works as it should and the separate PSU doesn't seem to to get warm, let alone hot. However, last night, after several hours use it tripped the mains circuit breaker when I switched it OFF. The house has a modern RCD circuit breaker unit next to the electricity meter and the main circuit breaker had been tripped. I had to switch off all the individual ring main circuit breakers before I could switch the main breaker back on and then switch on all the individual breakers for the separate mains circuits again. I switched the DAC-AMP back on this morning and it powers up and seems fine. This is the circuit for the PSU and the DAC-AMP. There is no fuse in the PSU itself, but there is a 3A fuse in the mains plug: Has anyone got any ideas as to what might be the most likely reason it would trip a circuit breaker when I switch it off? One thing that did occur to me is that the AMP has an on-off switch built into the volume pot. Therefor if I switch the amp off prior to switching off the mains switch the caps on the voltage regulator board have no where to "bleed" away to. Does that sound plausible?
|
|
rickcr42
Fully Modded
Rest in peace my good friend.
Posts: 4,514
|
Post by rickcr42 on Sept 20, 2006 12:27:32 GMT
if everything worked before and does now what was the difference at the time of the breaker trip ? it comes down to having too much current draw on that particular line for the breaker rating and either says dead short somewhere (not likely if everything works) or a surge from turning on too many devices for the breaker to handle the combination of BTW-toss a 10 ohm 1W resistor between your two 1KuF caps and lose the rest or better,replace them with x2 2,200uf with the resistor then toss a combination 10uF and 0.1uf on the output
|
|
xerxes
Been here a while!
Posts: 1,115
|
Post by xerxes on Sept 20, 2006 13:04:40 GMT
Hi Rick,
There was nothing different as far as I know. It happened quite late at night, so there wouldn't have been much on around the house at all. The circuit breakers are very sensitive, I have known them to trip when a light bulb blows. The fact that it happened when I switched the power off makes me wonder whether the caps on the voltage regulator board had enough charge to cause a spark in the switch as I switched off?
|
|
|
Post by PinkFloyd on Sept 20, 2006 15:54:07 GMT
Beautiful job xerxes! I mean, really really well done and so neat and tidy.... first class mate
|
|
xerxes
Been here a while!
Posts: 1,115
|
Post by xerxes on Sept 20, 2006 17:02:24 GMT
Thanks Mike, Although if it keeps tripping the mains circuit breaker, it's going to be annoying. I don't think its dangerous, but I'm going to get pretty sick of resetting the clocks on my radio alarm, the oven, microwave, etc. I'm a little baffled, as I was working with mains I was extra careful to ensure that there was no possibility of anything coming lose in the PSU and causing a short and that nothing could touch anything it shouldn't. The only thing I can think of is the issue I mentioned before, where the amp, which uses a little Alps pot which has an integral power switch can be switched off independantly of the PSU. The voltage regulator board contains five 3,300uF capacitors and the little Pimeta amp will run for ten or twenty seconds after the mains power is switched off. I think that previously I may have always switched the mains off first, so the caps discharged through the amp. If the amp is switched off first, the caps may hold enough charge to cause a spark in the mains switch which is sufficient to trip the mains RCD breaker; which does seem to be very sensitive. I'm going to have to try it out and see if I can repeat the problem. If this does turn out to be the case, I should be able to use a jumper so that the switch in the pot, doesn't actually power off the amp.
|
|
xerxes
Been here a while!
Posts: 1,115
|
Post by xerxes on Nov 14, 2006 0:43:24 GMT
I'm still having problems with my DAC/AMP/PSU whereby it occassionaly trips the mains RCD when I switch it off. I asked the voltage regulator board designer and he suggest that it could be caused by the chassis filter due to connection via the Cy caps to earth. To remedy this he suggests that I try a snubber accross the switch contact, something like the "Alternative Application" in this diagram: Sounds plausible, but I thought I'd run it by the experts here first.
|
|
rickcr42
Fully Modded
Rest in peace my good friend.
Posts: 4,514
|
Post by rickcr42 on Nov 14, 2006 4:30:45 GMT
damn are you in trouble if we are what passes for experts ;D but since you asked Yes.Good practice and something I always do being totally anal about pops,clicks,ticks,fuzz,hash,etc. I HATE any sounds that draw attention not intentional so go to great lengths to protect every manner of possibly irritation before it pisses me off and that cap across the switch contacts is a long time standard in commercial products.Just be sure to use AC rated caps of the proper voltage (WIMA has some high voltage snubber caps available )
|
|
xerxes
Been here a while!
Posts: 1,115
|
Post by xerxes on Nov 14, 2006 5:34:11 GMT
Hi Rick, This isn't so much as a "pops and clicks" issue, as a "b*llocks, its tripped the mains and I'm going to have to reset every bloody clock in the house again!", you know the ones on the oven, the microwave etc. that run on mains. I wear a wrist watch and wouldn't mind if they were all wrong, but the damn things sit there flashing until you set them. In any case, how about one of these: rswww.com/, stock number 209-229?
|
|
xerxes
Been here a while!
Posts: 1,115
|
Post by xerxes on Dec 6, 2006 5:35:04 GMT
Just a little update, I installed a snubber on the switch in the PSU and haven't had any problems with the tripping the mains RCD since. Also, I compared the Pimeta amp to my WNA MkII earlier today and I think I prefer the little Pimeta amp. The Pimeta amp seems more "spacious" and "airy", in comparison the WNA sounds less involving and perhaps a little soft and woolly. It's not night and day, and I could live with either amp, but given that the Pimeta is half the size and half the price, it's an interesting finding. I wonder what the PPA by the same designer is like, or possibly the PPA derived M3.
|
|
rickcr42
Fully Modded
Rest in peace my good friend.
Posts: 4,514
|
Post by rickcr42 on Dec 6, 2006 14:34:58 GMT
why not build the amp the M3 was copied from,the SDS Labs amp ? headwize.com/projects/showfile.php?file=stokes_prj.htmHas a simple stereo topology instead of the three channel architecture of the M3 which allows a lot more leeway on what it can be lashed up to without problems,being a simple Op Amp gain stage/Class-A current pump stage easily modded to suit,has great sonics plus with op amp "rolling" can be dialled in to suit your taste AND will drive a loudspeaker being a 4 Watt amp in AB mode (addition of a simple A/AB DPDT switch ). The one I have on the output of my 5/2 line mixer in the cue channel has a split box layout (amp/ext.ps) so has a very small footprint.Too small actually being so light it "walks" on the desk top from headphone cable weight so will need to have some mass added of be re-integrated with the psu for a one box amp but otherwise is probably the most multi-headphone freindy amp in house being able to drive anything thrown at it. Having a "normal" TRS jack connection on the output (2CH not 3) means easy switching of headphones or loudspeakers which again on mine is a three way Headphone A,Headphone B,Monitor make before break rotary (input is CUE 1,CUE 2,AUX) and there is a pcb available though not REAL cheap more than reasonable.The guy did afterall have to spend some time designing and testing the amp which should be worth something www.quadesl.com/refurb/refurb_headphone.html
|
|
xerxes
Been here a while!
Posts: 1,115
|
Post by xerxes on Dec 6, 2006 17:18:29 GMT
You know my thoughts on electronics sticking out of boxes. Pretty, glowing valves is bad enough; a bunch of ugly caps, heatsinks and a plastic encapsulated toroid is an absolute no-no. Seriosly though, given the less than stella outcome of my first "from the PCB up" build, I think it will be a while before I go there again. ;D I also reckon that by the time you've sourced all the components from several different suppliers and paid multiple delivery charges, building something from the PCB and components is no less expensive than buying assembled and tested modules, or even completed products from some of the small kit producers. Especially as you generally pay premium prices for low volumes of components or are forced to buy 5, 10 or even 50 items when you only need 1 or 2; although I suppose it gets cheaper as you build up a collection of commonly used components from the remainders of those over quanties. I really enjoyed building the CORDA amp, my soldering is neat enough, I have the dexterity and mechanical wherewithal to assemble things and the ability to follow instructions and put all the parts in right place. However, I don't really have the troubleshooting knowledge and experience to find the problem if whatever it is doesn't work once all the parts are in the right place. With mechanics it's easy, you can see it, hear it or feel it, electronics is a different kettle-o-fish.
|
|